Passive listening in wireless communication

ABSTRACT

Passive listening in wireless communication. An activity sensor device senses a packet. A medium access control (MAC) address parser receives the packet, processes a header of the packet, and activates a MAC device in response to recognizing a MAC address within the header, such that the MAC device is not activated if the MAC address parser does not recognize the MAC address.

TECHNICAL FIELD

Embodiments of the present invention pertain to the field of wirelesscommunication.

BACKGROUND

Data communication devices, such as wireless communication devices,typically employ Medium Access Control (MAC) functionality forcontrolling access to a physical transmission medium of the device.Typically, MAC functionality is implemented in software running on aprocessor. Moreover, data communication devices include a number ofother software applications running on a processor, applications forrendering and transmitting voice communication.

Current implementations of data communication devices typically employdual-core (e.g., two processors) architecture. Without two processors, asoftware MAC may introduce problems detrimentally affecting theperformance of the data communication device. For instance, modemfunctions and media processing using the software MAC have tightreal-time processing requirements. While other applications do not havethese tight real-time processing requirements, the application driversinclude disable interrupts for accessing a processor. These disableinterrupts interfere with real-time functions. In other words, theprocessing of the software MAC functions having tight real-timeconstraints and the other applications not having tight real-timeconstraints are mutually exclusive to a single processor, as a processorcan only be accessed once at any time. This fundamental incompatibilityis solved by multiple processors.

However, the design and modification of communication devices includingtwo processors is complex and expensive. Moreover, where one of theprocessors is a digital signal processor (DSP), as is typically thecase, the design and modification becomes even more complex andexpensive. DSPs require specialized toolsets and firmware, and softwareengineers who design DSPs require specialized training. Also, DSPs areconsiderably more expensive than standard processors. Furthermore, theoperation of two processors consumes more power and is more expensivethan the operation of a single processor.

SUMMARY

Various embodiments of the present invention, passive listening inwireless communication, are described herein. An activity sensor devicesenses a packet. A medium access control (MAC) address parser receivesthe packet, processes a header of the packet, and activates a MAC devicein response to recognizing a MAC address within the header, such thatthe MAC device is not activated if the MAC address parser does notrecognize the MAC address.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of present invention are illustrated by way of example, andnot by way of limitation, in the figures of the accompanying drawingsand in which like reference numerals refer to similar elements and inwhich:

FIG. 1 illustrates a block diagram of a voice over Internet Protocol(VoIP) communication device operating on a Reduced Instruction SetComputer (RISC) microprocessor, in accordance with one embodiment of thepresent invention.

FIG. 2 illustrates a software stack of the RISC microprocessor, inaccordance with one embodiment of the present invention.

FIG. 3 illustrates a block diagram of a voice over wireless local areanetwork (VoWLAN) communication device including a single microprocessor,in accordance with one embodiment of the present invention.

FIG. 4 illustrates a block diagram of a voice over wireless local areanetwork (VoWLAN) communication device including a single RISCmicroprocessor, in accordance with another embodiment of the presentinvention.

FIG. 5 illustrates a block diagram of hardware-centric medium accesscontrol (MAC) device, in accordance with one embodiment of the presentinvention.

FIG. 6 illustrates a block diagram depicting components of a VoWLANcommunication device used for proactive power control, in accordancewith one embodiment of the present invention.

FIGS. 7A, 7B, 7C and 7D are flow charts illustrating processes forproviding wireless communication using a single microprocessor, inaccordance with an embodiment of the present invention.

FIG. 8 illustrates a block diagram of a cellular/VoWLAN (CelluLAN) SoCincluding a single microprocessor, in accordance with one embodiment ofthe present invention.

FIG. 9 illustrates a block diagram of a CelluLAN communication deviceincluding a single RISC microprocessor, in accordance with anotherembodiment of the present invention.

FIG. 10 illustrates a block diagram of a baseband processing module, inaccordance with one embodiment of the present invention.

FIG. 11 is a flow chart illustrating a process for providing CelluLANcommunication using a single microprocessor, in accordance with anembodiment of the present invention.

DESCRIPTION OF EXAMPLE EMBODIMENTS

Reference will now be made in detail to particular embodiments of thepresent invention, examples of which are illustrated in the accompanyingdrawings. While the invention will be described in conjunction with theparticular embodiments, it will be understood that they are not intendedto limit the invention to these embodiments. On the contrary, theinvention is intended to cover alternatives, modifications andequivalents, which may be included within the spirit and scope of theinvention as defined by the appended claims. Furthermore, in thefollowing detailed description of embodiments of the present invention,numerous specific details are set forth in order to provide a thoroughunderstanding of particular embodiments of the present invention.However, it will be recognized by one of ordinary skill in the art thatembodiments of the present invention may be practiced without thesespecific details. In other instances, well-known methods, procedures,components, and circuits have not been described in detail as not tounnecessarily obscure aspects of the embodiments of the presentinvention.

Notation and Nomenclature:

Some portions of the detailed descriptions, which follow, are presentedin terms of procedures, steps, logic blocks, processing, and othersymbolic representations of operations on data bits within a computermemory. These descriptions and representations are the means used bythose skilled in the data processing arts to most effectively convey thesubstance of their work to others skilled in the art. A procedure,computer executed step, logic block, process, etc., is here, andgenerally, conceived to be a self-consistent sequence of steps orinstructions leading to a desired result. The steps are those requiringphysical manipulations of physical quantities. Usually, though notnecessarily, these quantities take the form of electrical or magneticsignals capable of being stored, transferred, combined, compared, andotherwise manipulated in a computer system. It has proven convenient attimes, principally for reasons of common usage, to refer to thesesignals as bits, values, elements, symbols, characters, terms, numbers,or the like.

It should be borne in mind, however, that all of these and similar termsare to be associated with the appropriate physical quantities and aremerely convenient labels applied to these quantities. Unlessspecifically stated otherwise as apparent from the followingdiscussions, it is appreciated that throughout the particularembodiments of the present invention, discussions utilizing terms suchas “receiving” or “transmitting” or “performing” or “providing” or“requiring” or “fragmenting” or “defragmenting” or “activating” or“deactivating” or “recognizing” or “controlling” or “outputting” or“rendering” or “executing” or “forwarding” or “sensing” or “decoding” or“determining” or “processing” or the like, refer to the action andprocesses of a single-processor voice communication device, e.g., voiceover Internet Protocol (VoIP) system in a chip (SoC) 100 of FIG. 1,voice over wireless local area network (VoWLAN) SoC 300 of FIG. 3,VoWLAN communication device 400 of FIG. 4, cellular/VoWLAN (CelluLAN)SoC 800 of FIG. 8, and CelluLAN communication device 900 of FIG. 9, orsimilar electronic computing device, that manipulates and transformsdata represented as physical (electronic) quantities within the computersystem's registers and memories into other data similarly represented asphysical quantities within the computer system memories or registers orother such information storage, transmission or display devices.

DSP-less VoIP

FIG. 1 illustrates a block diagram of a voice over Internet Protocol(VoIP) system in a chip (SoC) 100 using a single processor. Variousdescribed embodiments provide VoIP that is performed as softwareexecuted on a general purpose microprocessor, such as a ReducedInstruction Set Computer (RISC) microprocessor. The describedembodiments detail numerous optimizations that allow for providing VoIPusing a single microprocessor. In particular, embodiments of the presentinvention provide for VoIP functionality within a single microprocessorwithout the need for a dedicated digital signal processor (DSP).

VoIP SoC 100 includes a single microprocessor 110, in accordance withone embodiment of the present invention. VoIP SoC 100 includesmicroprocessor 110, Internet Protocol (IP) connection 115, systemperipheral controller 125, system memory controller 130 and audio codec135, all communicatively coupled over bus 105. It should be appreciatedthat VoIP SoC 100 may include additional components, as understood bythose of skill in the art. These additional components are not describedherein so as to not obscure the embodiments described herein.

It should be appreciated that bus 105 illustrates that each of thecomponents of VoIP SoC 100 are communicatively coupled. However, itshould be appreciated that bus 105 can be implemented as a central bus,as shown, individual interconnections between the individual components,or any combination of buses and individual interconnections. Inparticular, it should be appreciated that bus 105 is not intended to belimited by the shown embodiment.

In one embodiment, microprocessor 110 is operable to perform allnecessary operations associated with VoIP communication, includingdigital signal processing and control functions. In particular,microprocessor 110 is not a dedicated DSP. In one embodiment,microprocessor 110 is a multi-purpose processor, such as a centralprocessing unit (CPU). In one embodiment, microprocessor 110 is a RISCmicroprocessor. Details specifying the operation of a RISCimplementation of microprocessor 110 are described below in accordancewith FIG. 2.

IP connection 115 is operable to communicate with an IP network 118, soas to provide VoIP communication over IP network 118. It should beappreciated that IP connection 115 is operable to communicate with IPnetwork 118 over a wired or wireless connection. System peripheralcontroller 125 is communicatively coupled to external system peripherals140 that include additional components that provide added functionalityto VoIP SoC 100. System memory controller 130 is communicatively coupledto external memory 145 for use in operating VoIP SoC 100. Externalmemory 145 may include volatile memory, such as RAM, SRAM, and SDRAM(Mobile SDRAM or DDR, Cellular RAM etc), and non-volatile memory, suchas EEPROM, and NOR or NAND flash. It should be appreciated that externalmemory 145 may include multiple types of memory, all of which arerepresented as external memory 145.

Audio codec 135 is operable to encode and decode audio data for use incommunicating voice data using VoIP. It should be appreciated that audiocodec 135 may be implemented as hardware, software, firmware, or anycombination thereof. In one embodiment, audio codec 135 provides forcoupling VoIP SoC 100 to an external device for rendering the voicecommunication and for receiving voice communication. In one embodiment,audio codec 135 is coupled to voice headset 138. However, it should beappreciated audio codec 135 may be coupled to many different types ofdevices and interfaces, including but not limited to Foreign ExchangeSubscriber (FXS) interfaces, Foreign Exchange Office (FXO) interfaces,microphones, and speakers.

FIG. 2 illustrates a software stack 200 of an embedded RISCmicroprocessor, in accordance with one embodiment of the presentinvention. Software stack 200 illustrates operations and applicationexecuted by a RISC microprocessor, e.g., microprocessor 110 of FIG. 1.In one embodiment, software stack 200 includes the followingapplications: voice application and user interface 202, applicationlayer 204, multi-channel VoIP system framework 206, call manager 208,packetization 210, VoIP Protocol, SIP stack and user agent 212, adaptivejitter buffer 214, RTP/RTCP 216, operating system (OS) abstraction layer218, TCP/IP, UDP and NAT 220, OS 222, and MAC control layer 224. Itshould be appreciated that applications 202-224 are applicationstypically included in standard VoIP implementations, and arewell-understood by those of skill in the art. Specific operation detailsof these applications are not included herein, so as to not obscure thedescribed embodiments. In one embodiment, the RISC processor also runs aMAC control layer and/or firmware under the OS.

Software stack 200 also includes voice processing applications andoperations, collectively identified as SoftDSP 250. The voice processingapplications of SoftDSP 250 necessitate significant computationalrequirements which typically have been addressed by having a separateDSP processor which has specialized hardware support to efficiently mapthe arithmetic computations in these operations on a programmablearchitecture. The DSP is always used in conjunction with a generalpurpose RISC microprocessor which typically handles all the controlfunctions, e.g., application 202-224. In one embodiment, SoftDSP 250applications include vocoder 252, packet loss concealment 254, telephony256, and line/acoustic echo canceller 258. The operational details ofapplications 252-258 are well-understood by those of skill in the artand are not included herein, so as to not obscure the describedembodiments.

In order to implement voice processing applications of SoftDSP 250 on aRISC microprocessor, it is necessary to minimize data loading fromexternal memory (e.g., SDRAM) to internal registers of the RISCmicroprocessor. In one embodiment, data loading is minimized byimproving data locality for block processing of loaded data. RISCarchitectures are load-store, which essentially requires that every dataelement needs to be loaded to in internal registers before the elementcan be operated on. Each load operation requires one or more cyclecycles depending upon the availability of the data in cache. Forexample, considering that all successive MAC operations, e.g., MultiplyAccumulate Multiply Add operations, in a computational loop typicallyrequire at least one unique operand, an operation implementing tenmillion MACs may require at least seventeen to twenty million loadoperations to be performed along with the ten million MACs, thussubstantially increasing the cycles required for completing these 10million MAC operations.

One of the properties of the operations is that they are iterative andmost data elements are used multiple times by the MAC operations duringthe execution of these iterative loops, but in most cases the operationswhich make use of common data elements are computationally farseparated. Typically, most computational loops are structured such thatthey are oriented for computational locality where most data elementsrequired for these computations are distributed, meaning mostconsecutive computations require unique data elements to be loaded hencediscarding the existing data in the registers. Also, the discarded dataneeds to be reloaded to the registers from external memory during thenext iteration of the loop when it is required hence resulting insubstantial overhead.

One of the mechanisms of reducing the overhead is by loading theoperands in the RISC microprocessor's internal registers in specificblock sets and then realigning the inner and outer computational loopssuch that only specific sections of the operation are executed in whichthe computations require only these data elements which are available inthe registers at that specific instance. This achieves much higher dataloading efficiency, e.g., data locality allows for the execution of MACand other arithmetic computations with least number of cycles wasted inloading data from external memory to internal registers. In oneembodiment, the re-loading of data is minimized by reorganizing theloops for data locality rather than computational locality, e.g.,instead of implementing nearest neighbor computation successively, thecomputation is distributed logically but requires the same data elementswhich are available in the RISC microprocessor's internal register. Inone embodiment, the loops are re-oriented from the traditionalsequential processing to a block processing structure such that eachblock requires only those elements, which are available in theregisters.

It should be appreciated that the efficiency that can be achieved usingdata locality depends on the numbers of available registers. In oneembodiment, the number of available registers that can be used for blockprocessing is maximized by identifying the registers which containrelevant data but are not required during the processing of the loop andtemporarily saving these registers on the stack and making themavailable as scratch registers. These registers are restored back totheir original state from the stack after the execution of the loop hasbeen completed.

With some RISC microprocessor architectures it is feasible to use theupper 16-bit and lower 16-bit of a 32-bit register as separate signedinteger operands for arithmetic operations. In one embodiment, thisfeature is used to load two successive 16-bit signed data elements usinga single 32-bit unsigned load operation and use them as two separate16-bit data elements in arithmetic computations. Using this method alongwith block load and processing described above, the data loadingefficiency is further significantly improved as exemplified below.

Another arithmetic operation is to check for overflow and underflow ofaccumulated results while performing left bit shifting operations foradjusting the fixed point Q format of the Accumulated results. Duringthis left shifting of bits of accumulated results, overflow or underflowcan occur, which needs to be identified and the operand should berounded off to either MIN or MAX value. For implementing arithmetic leftshift of a 32 or 16-bit signed value M by N bits with overflowdetection, previous solutions were typically iterative. The iterativeapproach requires implementing one bit shift at a time and checking foroverflow at the end of each iteration, thus requiring N iterations. Thepresent embodiment determines guard bits for ensuring against overflowwithout requiring N iterations. The present embodiment determines guardbits using an arithmetic function by determining if the signed number Mwill overflow if it is left shifted by N bits. The present embodimentsignificantly reduces the clock cycles compared to the previously usediterative method. The arithmetic solution takes 2-4 clock cycles.

Various embodiments of the present invention provide a VoIP solutionthat does not require a DSP. This is accomplished by optimizing ageneral microprocessor, such as a RISC processor, for performing voiceprocessing. By removing the requirement for a DSP in VoIPcommunications, the described embodiments provide a lower cost solutionfor VoIP communications.

DSP-less VoWLAN

FIG. 3 illustrates a block diagram of a voice over wireless local areanetwork (VoWLAN) SoC 300 including a single microprocessor 310, inaccordance with one embodiment of the present invention. VoWLAN SoC 300includes microprocessor 310, WLAN baseband 315, system peripheralcontroller 325, system memory controller 330 and audio codec 335, allcommunicatively coupled over bus 305. It should be appreciated thatVoWLAN SoC 300 may include additional components, as understood by thoseof skill in the art. These additional components are not describedherein so as to not obscure the embodiments described herein.

It should be appreciated that bus 305 illustrates that each of thecomponents of VoWLAN SoC 300 are communicatively coupled. However, itshould be appreciated that bus 305 can be implemented as a central bus,as shown, individual interconnections between the individual components,or any combination of buses and individual interconnections. Inparticular, it should be appreciated that bus 305 is not intended to belimited by the shown embodiment.

In one embodiment, microprocessor 310 is operable to perform allnecessary operations associated with VoIP communication, includingdigital signal processing and control functions. In particular,microprocessor 310 is not a dedicated digital signal processor (DSP). Inone embodiment, microprocessor 310 is a multi-purpose processor, such asa CPU. In one embodiment, microprocessor 310 is a RISC microprocessor.For example, the RISC microprocessor may be implemented as one of twogeneral classes, one with signaling and signal processing algorithmsimplemented in software on the RISC micro-controller as in, e.g., asoftDSP, and second where some of the signal processing blocks areimplemented in hardware to reduce MIPS load on the RISC.

It should be appreciated that microprocessor 310 is operable to provideVoIP communications in accordance with the various embodiments describedin accordance with FIGS. 1 and 2.

WLAN baseband 315 is operable to communicate with an IP network 318 overa wireless connection using external WLAN radio 340 comprising antenna322, so as to provide VoIP communication over IP network 318. In oneembodiment, WLAN baseband 315 includes a physical layer (PHY) device 360and a medium access control (MAC) device 365. In one embodiment, MACdevice 365 is a hardware device that is configured to perform real-timevoice communication functions independent of microprocessor 310. Oneembodiment of the operation of MAC device 365 is described in FIG. 5.

System peripheral controller 325 is communicatively coupled to externalsystem peripherals 345 that include additional components that provideadded functionality to VoIP VoWLAN 300. System memory controller 330 iscommunicatively coupled to external memory 350 for use in operating VoIPVoWLAN 300. External memory 350 may include volatile memory, such asRAM, SRAM, and SDRAM, and non-volatile memory, such as EEPROM, and NORor NAND. It should be appreciated that external memory 350 may includemultiple types of memory, all of which are represented as externalmemory 350.

Audio codec 335 is operable to encode and decode audio data for use incommunicating voice data using VoIP. It should be appreciated that audiocodec 335 may be implemented as hardware, software, firmware, or anycombination thereof. In one embodiment, audio codec 335 provides forcoupling VoIP VoWLAN 300 to an external device for rendering the voicecommunication and for receiving voice communication. In one embodiment,audio codec 335 is coupled to voice headset 338. However, it should beappreciated audio codec 335 may be coupled to many different types ofdevices and interfaces, including but not limited to FXS interfaces, FXOinterfaces, microphones, and speakers.

It should be appreciated that VoWLAN SoC 300 provides for voicecommunication over a WLAN without requiring the use of a dedicated DSPas well as a general-purpose microprocessor. In particular, VoWLAN SoC300 is operable to perform voice processing on the general-purposemicroprocessor 310 (e.g., a RISC microprocessor). Microprocessor 310 isconfigured to provide all voice processing and control functionality foroperation of VoWLAN SoC 300.

FIG. 4 illustrates a block diagram of a VoWLAN communication device 400including a single RISC microprocessor 402, in accordance with anotherembodiment of the present invention. VoWLAN Communication device 400includes VoWLAN SoC 401, which operates in a similar manner as VoWLANSoC 300 of FIG. 3 to provide voice processing and control functionalitywithout a separate DSP microprocessor. VoWLAN SoC 401 includes twobuses, a high-speed bus 408, e.g., operating at 66 MHz, and a peripheralbus 426, e.g., operating at 33 MHz.

VoWLAN SoC 401 includes NAND memory controller (NANDC) 410 which may becoupled to external flash memory (e.g., NAND Flash 456), SDRAMcontroller (SDRAMC) 414 which may be coupled to external SDRAM 464,direct memory access controller (DMAC) 415, liquid crystal displaycontroller (LCDC) 416 which may be coupled to LCD display 466, localmemory controller (LMC) 434 that is coupled to boot ROM 412, high speedbus (AHB) controller 406, Universal Serial Bus (USB) controller 404coupled to USB (e.g., USB 1.1 or USB 2.0) On-The-Go (OTG) PHY 460, whichmay be coupled to external USB port 462, and Vector Interrupt Controller(VIC) 438, which communicate over high speed bus 408.

VoWLAN SoC 401 also includes power management (PMU) 436, watchdog timer442, real-time clock (RTC) 428, timer 432, In-Circuit Emulator (ICE)module 450, Universal Asynchronous Receiver-Transmitter (UART) 446,phase-locked loop (PLL) 430, key pad 452, Serial Synchronous Interface(SSI) 444, Inter-integrated Circuit (12C) communication interface 445,Inter-Integrated Circuit Sound (12S) 448, general purpose I/O (GPIO)449, secure digital I/O (SDIO) 454, and power management 457, whichcommunicate over peripheral bus 426. SSI 444, 12C interface 445, UART446, 12S 448, SDIO 454, and GPIO 449, may be coupled to externaldevices, e.g., a voice headset. It should be appreciated that the voiceheadset may be any device operable to receive and render voicecommunication.

High speed bus 408 and peripheral bus 426 are communicatively coupledover bus bridge (BRG) 440. The operations of various components ofVoWLAN communication device 400 are understood by those of skill in theart. These components are not described herein so as to not obscure theembodiments described herein.

In one embodiment, RISC microprocessor 402 is operable to perform allnecessary operations associated with VoIP communication, includingdigital signal processing and control functions. In particular, RISCmicroprocessor 402 does not require the use of a dedicated DSP toperform signal processing. RISC microprocessor 402 is configured toprovide all voice processing and control functionality for operation ofVoWLAN communication device 400. In one embodiment, RISC microprocessor402 includes data cache (D-cache) for caching data and an instructioncache (I-cache) for caching instructions.

VoWLAN communication device 400 is operable to provide VoIPcommunication over an IP network over a wireless connection using awireless baseband and external radio 468. In one embodiment, VoIPtraffic transmitted through radio 468, both in transmission andreception, are controlled by PHY device 420, MAC device 418, and ADC/DACinterface (I/F) 422. PHY device 420, MAC device 418, and ADC/DAC I/F 422may be collectively referred to herein as a wireless baseband module. Inone embodiment, ADC/DAC I/F is controlled by clock signal 421, e.g., 40MHz, and includes PLL 423. In one embodiment, MAC device 418 is ahardware device that is configured to perform real-time voicecommunication functions independent of RISC microprocessor 402. In oneembodiment PHY device 420 is an 802.11abg PHY digital baseband device.In one embodiment, MAC device 418 is an 802.11abgei MAC 40/20 MHzdevice. One embodiment of the operation of MAC device 418 is describedin FIG. 5.

FIG. 5 illustrates a block diagram of hardware-centric MAC device 418,in accordance with one embodiment of the present invention. It should beappreciated that hardware-centric MAC device 418 may used as MAC device365 of FIG. 3, MAC device 865 of FIG. 8, and the MAC device of WLANtransceiver 925 of FIG. 9. As shown, MAC device 418 is communicativelycoupled to RISC microprocessor 402, host memory 550, (e.g., SDRAM 464),and other peripherals 502, e.g., LCD display 466, over high speed bus408. In the present embodiment, MAC device 418 is implemented as ahardware device configured to perform real-time voice communicationfunctions independent of RISC microprocessor 402. In one embodiment,RISC microprocessor 402 includes a MAC driver for controllingconfiguration settings of MAC device 418. For example, the MAC driverallows for the configuration of channel selection, data transferparameters, and other functions that do not occur during WLANcommunication. In particular, in the present embodiment, the MAC driverdoes not wake RISC microprocessor 402 during WLAN communications. In oneembodiment, most of the data processing blocks of MAC device 418 areimplemented in hardware and a thin control logic runs on the RISCmicroprocessor 402 making MAC processing of the received and transmittedvoice packets decoupled from the microprocessor for all practicalpurposes.

In particular embodiments, MAC device 418 is configured to providewireless communication at very high data rates, e.g., 108 MBPS. In orderto provide data transfer at increased data rates while not increasingcycle consumption of RISC microprocessor 402, MAC device 418 operatesindependent of RISC microprocessor 402. MAC device 418 providesreal-time MAC functionality into the gate logic. All hard real-timingrequirements, such as Short Inter-Frame Space (SIFS), DistributedInter-Frame Space (DIFS), AIFS arbitration inter-Frame space and PointCo-ordination Inter-Frame Space (PIFS) timing requirements are handledentirely by MAC that is implemented in the gate logic, also referred toherein as real-time logic (RTL).

MAC device 418 includes bus specific interface 504 for interfacing withhigh speed bus 408 and host bus interface modules 506. For example,embodiments bus specific interface 504 may include, but are not limitedto a Peripheral Component Interconnect (PCI)/Advanced High-performanceBus (AHB) interface, a Direct Memory Access (DMA) interface, a slaveinterface, or another type of interface. Host bus interface modules 506include transmit (T_(x)) and receive (R_(x)) power save handlers (e.g.,for user configurability).

MAC device 418 also includes control plane modules 508 for providingcontrol functions of MAC device 418 and hardware media access plane 520communicatively coupled to control plane modules 508 and for performingreal-time data communication functions independent of RISCmicroprocessor 402. In particular embodiments, media access plane 520 isoperable to handle operations having high real-timing requirements. Forexample, media access plane is operable to handle all operations havingrequirements on the order of microseconds. In particular embodiments,control plane module 508 is operable to handle less stringent timingrequirements, e.g., on the order of tens of milliseconds. By placing alesser processing burden on the control plane modules 508, in particularembodiments, control plane modules 508 may be implemented in software,firmware, hardware or any combination thereof.

In particular embodiments, where at least a portion of control plane 508is implemented as software, the portion of control plane 508 may beimplemented in programmable hardware, e.g., programmable logic. Byimplementing at least a portion of control plane modules 508 asprogrammable hardware, programmable registers of the programmablehardware can be used to account for any potential interoperability orextensibility problems resulting from interrupt conflicts. Usingprogrammable hardware allows for solving real-time operating constraintsin a system using a single microprocessor while stile maintaining ahardware-centric MAC 418 that is configurable to supportinteroperability or extensibility.

Control plane modules 508 provide RTL-based control plane moduleimplementation for a number of features as defined by Institute ofElectrical & Electronics Engineers (IEEE) standards. These features mayinclude, but are not limited legacy power save, APSD power savefeatures. In one embodiment, control plane modules 508 are configurablesuch that features implemented by control plane modules 508 may be movedto software and/or firmware, with minimal changes to RTL code. In oneembodiment, control plane modules may be implemented in programmablehardware. Control plane modules 508 includes RTL implemented StationManagement Entity (SME) 510, which is configured to monitor andoptionally initiate various power save features.

Media access plane 520 of MAC device 418 provides real-time MACfunctionality. In one embodiment, media access plane 520 is implementedin gate logic, e.g., RTL, such that real-timing requirements of MACdevice 418 are handled in gate logic. Media access plane 520 includesreceive packet memory 522 and transmit packet memory 526. In oneembodiment, receive packet memory 522 and transmit packet memory 526 areimplemented as RAM memory using First In, First Out (FIFO) storage.

In one embodiment, MAC device 418 performs polling of stations in IBSSmode without the intervention of firmware for tracking information suchas the Announcement Traffic Indication Message (ATIM) period. MAC device418 also provides for RTL controlled packet transfer when a stationresponds for ATIM polls for IBSS.

MAC device 418 comprises fragmentation engine 534 for providingreal-time fragmentation without requiring intervention of software atthe MAC Protocol Data Unit (MPDU) level. MAC device 418 also comprisesde-fragmentation engine 528 for providing real-time reassembly withoutrequiring intervention of software at the MPDU level.Encryption/decryption engine 530 is operable to provide on-the-flyencryption/decryption with RTL based Key Retrieval merged withon-the-fly fragmentation and reassembly of fragmentation engine 534 andde-fragmentation engine 528, respectively.

Beacon process module 536 and beacon generation module 546 providebeacon synchronization and generation of timing based on a hardware 64bit clock. In one embodiment, beacon process module 536 is alsoconfigured to perform beacon filtering after join in response to arequest by software. In particular embodiments, beacon process module536 is operable to receive packets from packet process unit 542 and tofilter out unwanted packets, e.g., non-beacon packets, in hardware. Forexample, in particular embodiments, the filtering of unwanted packets isperformed without requiring the use of other components of MAC device418 and without requiring the use of RISC microprocessor 402.

In particular embodiments, beacon process module 536 is operable todeactivate after processing a packet and to activate in advance ofreceipt of a packet. In particular embodiments, beacon process module536 is operable to reactivate prior to receipt of a packet by a time atleast long enough to account for clock drift.

MAC device 418 comprises channel access engine 538 for providing channelaccess mechanisms. Channel access engine 538 is operable to provideContention Period (CP) Access, such as CP with Distributed CoordinationFunction (DCF), and Hybrid Co-ordination Function with Hybridcoordination function (HCF) controlled channel access (HCCA). MAC device418 also includes receive packet process unit 542 and transmit packetgeneration/transmit packet process unit 540. Physical Layer ConversionProtocol (PLCP) interface 544 provides an interface between MAC device418 and PHY device 420 of FIG. 4.

Hardware MAC device 418 implemented in RTL provides many functional andoperation advantages. MAC device 418 reduces the Million InstructionsPer Second (MIPS) requirement of VoWLAN SoC 401. For instance, the peakMIPS required to process the time critical Interrupt Service Routines(ISRs) is reduced to process those events. In one embodiment, theprocessing of the ISRs adheres to SIFS, DIFS, back-off, ExtendedInterframe Space (EIFS), Arbitration Interframe Space (AIFS) timingrequirements etc. Furthermore, the reduced numbers of interrupts persecond and the reduced number of types of interrupts simplifies softwarearchitecture.

In one embodiment, MAC device 418 obviates the need for spending MIPS onfragmentation/reassembly, since fragmentation and reassembly isperformed by the RTL. Software operating on RISC microprocessor 402configures the MAC Service Data Unit (MSDU) packet and process of thefragmentation and reassembly occurs opaque to firmware.

Moreover, by implanting encryption and decryption in RTL, RISCmicroprocessor 402 does not need to perform encryption/decryption.Furthermore, since the encryption/decryption is on-the-fly, firmwareMIPS are saved while moving the data packets back and forth from theencryption/decryption engines. Also, since encryption is on-the-fly,system firmware/software complexity is reduced in terms of numberinterrupts for co-coordinating encryption/decryption engines for receiveas well as transmit packets.

With reference to FIG. 4, in one embodiment, VoWLAN SoC 401 includestransmit power control (TPC) 424 for proactively controlling power toreduce power dissipation while in transmit mode. Excessive powerdissipation is a problem typically found in WLAN-enabled portabledevices that are powered from built-in batteries. Excessive power drainreduces effective up-time of these devices. It should be appreciatedthat transmit power control 424 may be integrated into any WLAN-basedSoC architecture for yielding significant reduction in transmit poweryet not compromising over-all throughput, and is not limited to thepresent embodiment. In one embodiment, transmit power control 424 istailored for voice traffic in a VoWLAN scenario, however transmit powercontrol 424 can be applied to data and video as well without any loss ofgenerality.

Transmit power control 424 is operable to establish a referenceoperating point and tracks the reference point over the entire session.Transmit power control 424 gets inputs from the receiver chain whenVoWLAN SoC 401 is in receive mode and uses these inputs to determine thecombination of the best 3-tuple operating point (transmit_power,data_rate, transmit_antenna) for a given transmit payload.

In one embodiment, transmit power control 424 uses periodicity of theVoIP based packets to monitor the operating reference point. Transmitpower control 424 has two modes of operation, active and stand-by,corresponding to a two-way voice call and stand-by mode of the WLAN,respectively. The operation of transmit power control 424 is based onthe following observations:

-   -   1. Channel reciprocity between Access Point (AP) and Station        (STA)    -   2. Channel varies slowly with time, e.g., a very low Doppler        (>100 msec).    -   3. Noise figure is more or less same in all devices (5 to 7 dB).

In the active mode, the transmit power control 424 tracks and controlsthe transmit power for each VoIP packet over WLAN at the same time makesa decision on the data rate and which antenna to be used yielding theleast power drain from the battery.

In one embodiment, transmit power control 424 establish a referenceoperating point (transmit_power, tx_data_rate, transmit_antenna) with agiven AP while getting associated. The Signal to Noise ratio (SNR) isthen computed from the received signal (from the given AP). A delayspread of the channel is estimated from the received signal (from thegiven AP). The best received antenna giving maximum signal strength forthe given AP is found. The minimum SNR needed for the packet to bedecoded successfully at the AP at the reference data rate for a givenpayload is estimated, which is required for the next transmit.

The transmit power needed to meet the minimum SNR requirement iscalculated. The minimum SNR and transmit power are recalculated withimmediate upper and lower data rates from the reference data rate. Theoptimal combination of rate and transmit power which drains minimumbattery energy is determined. The packet is transmitted with the optimaltransmit power and rate.

An acknowledgement (ACK) is received. The ACK is used to compute theSNR, the delay spread, and to determine the best received antenna givingmaximum signal strength for the given AP. The reference operating pointis updated with the parameters of the last transmit packet. The packetis re-transmitted with next lower rate with same power if no ACK isreceived. The SNR, the delay spread, and the best received antennagiving maximum signal strength for the given AP are updated based on thereceived VoIP packet.

The reference estimates are refreshed each time a successful transmithappens, which transmit power control 424 tracks through successfulreception of the ACK. The periodic nature of the voice traffic ensuresthat the reference typically gets updated every 20 or 30 msec, dependingon the type of speech coder selected.

In stand-by mode, the transmit power control 424 wakes up periodically(e.g., controlled by a heart-beat module) to receive beacon andrefreshes the reference receive parameters, which is 3-tuple(rx_signal_strength, rx_data_rate, rx_antenna). In one embodiment,transmit power control 424 wakes up periodically with every beacon or asdirected by the heart-beat module. In particular embodiments, transmitpower control 424 may wake up when beacon process module 536 of FIG. 5is woken up for processing a beacon. The SNR and signal strength areestimated from the received beacon. The delay spread of the channel isestimated from the received beacon. The best received antenna givingmaximum signal strength for the given AP is determined. The referencereceive parameters are updated with the latest successful match receive,e.g., a 32 bit Cyclic Redundancy Checksum (CRC-32).

In one embodiment, when VoWLAN SoC 401 enters into the active modeeither by a trigger from the application processor with an intension ofVoIP packet transmit or triggered by a traffic information map (TIM) inthe beacon, transmit power control 424 derives 3-tuple referenceoperating point from the 3-tuple reference receive parameters bydetermining the optimal transmit data rate and power for the givenpayload from the reference receive power and delay spread. The transmitantenna is set to the same as that of the reference receive parameter.The transmit_power, data_rate and antenna are set as the referenceoperating point upon a successful transmit.

FIG. 6 illustrates a block diagram 600 depicting components of a VoWLANcommunication device used for proactive power control, in accordancewith one embodiment of the present invention.

Conventional WLAN implementations require a PHY layer to decode alldetected packets and deliver the payload to the MAC layer. In aninfrastructure mode, an AP delivers the packets to the intendedstations. In such a scenario a majority of the packets decoded areactually not intended for the wireless STA. This results in excessivepower drain in decoding un-intended traffic.

WLAN is used to deliver packetized voice to the end-user over wireless‘hot-spots’. In one embodiment, VoWLAN communication device 400 isimplemented on a battery-powered hand-held device, requiring powerefficiency to increase talk time and standby time of device 400. In oneembodiment, VoWLAN SoC 401 is configured to perform passive listening tosave power during the presence of un-intended traffic.

In performing passive listening, PHY device 420 is partly aware of MACfunctionality and discards unintended traffic before waking up MACdevice 418. Radio 468 is operable to receive signals, e.g., RF and/ormixed signals. Activity sensor 602 comprises RF and mixed signal module604 and energy detection module 606 for sensing activity received overradio 468. RF and mixed signal 604 and energy detection module 606 arethe only components illustrated in FIG. 6 that are turned on by default.RF and mixed signal 604 and energy detection module 606 are configuredto sense the presence of activity on the channel. It should beappreciated that all other PHY and MAC modules are in shutdown.

In one embodiment, activity sensor 602 is operable to sense asilence-to-energy event. This ensures PHY device 420 is not triggeredwhen the WLAN wakes up in the middle of a packet on-the-air, but onlygets activated when silence gets detected at the end of current packetfollowed by another packet on-the-air activating energy detection (ED).If activity is detected, then ED module 606 triggers PHY device 420 forfurther processing.

PHY device 420 starts decoding the packet. The decoded bytes are passedon to MAC address parser module 608. In one embodiment, the decodedbytes passed on to MAC address parser module 608 includes at least aheader block of the packet. In particular, MAC address parser module 608receives the decoded bytes before waking up MAC 418. PHY device 420 is“MAC aware” such that MAC address parser module 608 knows the MACaddress of the STA. MAC address parser module 608 parses the decodedbytes for this address. If a match is detected, PHY device 420 wakes upMAC device 418. Alternatively, if a match does not occur, then activitysensor 602, PHY device 420 and MAC address parser module 608 are put inshutdown mode until the end of the unintended packet. In particularembodiments, shutdown/wake-up control 610 controls the shutdown (e.g.,deactivation) and wake-up (e.g., activation) of at least one of activitysensor 602, PHY device 420 and MAC address parser module 608. Thesecomponents are placed in shutdown by using the information of packetduration, which PHY device 420 decodes in the header and uses only ifheader-check (e.g., CRC-16) passes. Shutdown/wake-up control 610automatically wakes up activity sensor 602 at the end of the unintendedpacket.

In particular embodiments, in active mode, passive listening makes sureMAC device 418 gets activated when a beacon (broadcast), RTS-CTS(request to send and clear to send), multi-cast or uni-cast packetarrives. In one embodiment, management or control packets from theassociated AP are always decoded. This ensures correct functioning ofthe virtual carrier sensing mechanism and station management presentinside MAC device 418. This ensures shutting down of the applicationprocessor, e.g., RISC microprocessor 402, and core hardware MAC device418 for longer duration and saving power.

In standby mode, when the WLAN wakes up periodically to look for beacon,RF and mixed signal module 604 has to wake up in advance to take care ofthe RF and PLL delay, and to make sure beacon is not missed due to thedrift in the real time clock (RTC), e.g., a 32.768 kHz real time clock.This over-all time period by which various components, e.g., the RF,PLL, ADC, etc., have to wake up can be as long as 5 msec or moredepending on the extent of clock drift. Passive listening filters outall unwanted packets without switching on all components of MAC device418 and the RISC microprocessor 402 while waiting for beacon arrival. Inparticular embodiments, beacon process module 536 and packet processunit 542 are activated to perform the beacon processing. Also, while instandby, the RISC microprocessor can be totally in sleep as beaconprocessing can entirely be done in hardware MAC and thereby saving lotof power in frequent wake-up and shutting down the processor core. Inparticular embodiments, MAC device 418 is shut down after performingbeacon processing.

FIGS. 7A, 7B, 7C and 7D are flow charts illustrating processes 700, 730,750 and 770, respectively, for providing VoWLAN communication using asingle microprocessor, in accordance with an embodiment of the presentinvention. In one embodiment, processes 700, 730, 750 and 770 arecarried out by processors and electrical components under the control ofcomputer readable and computer executable instructions. The computerreadable and computer executable instructions reside, for example, indata storage features such as computer usable volatile and non-volatilememory. However, the computer readable and computer executableinstructions may reside in any type of computer readable medium.Although specific steps are disclosed in processes 700, 730, 750 and770, such steps are exemplary. That is, the embodiments of the presentinvention are well suited to performing various other steps orvariations of the steps recited in FIGS. 7A, 7B, 7C and 7D. Inparticular embodiments, processes 700, 730, 750 and 770 are performed bya VoWLAN communication device, e.g., VoWLAN SoC 300 of FIG. 3 or VoWLANcommunication device 400 of FIG. 4.

Process 700 of FIG. 7A illustrates steps for receiving VoWLANcommunications at a voice communication device including a singleprocessor. At step 702, VoIP traffic is received at a voicecommunication device of a wireless connection from a WLAN. In oneembodiment, as shown at step 704, the VoIP traffic is received at a PHYdevice, e.g., PHY device 420 of FIG. 4, of the wireless transceiver. Inone embodiment, a method of performing passive listening performed inconjunction with the PHY device is provided. Passive listening isperformed prior to waking a MAC device of the wireless transceiver.

With reference to FIG. 6 and FIG. 7B, steps in a process 730 forperforming passive listening are illustrated. At step 732, a packet issensed at activity sensor device 602. In a particular embodiment, asshown at step 734, activity sensor device 602 is deactivated subsequentsensing the packet. In one embodiment, activity sensor device 602 isdeactivated for at least a length of said packet. In a particularembodiment, as shown at step 735, PHY device 420 is activated subsequentsensing the packet for receiving the packet. It should be appreciatedthat steps 734 and 735 may be executed in series, in parallel, oroverlapping. At step 736, at least a header portion of the packet isdecoded at PHY device 420, where the header portion includes adestination medium access control (MAC) address. In a particularembodiment, as shown at step 737, MAC address parser 608 is activatedsubsequent decoding the header portion of the packet. In a particularembodiment, as shown at step 738, PHY device 420 is deactivatedsubsequent decoding the header portion of the packet. It should beappreciated that steps 737 and 738 may be executed in series, inparallel, or overlapping.

At step 740, it is determined whether the MAC address of the packet isrecognized at MAC address parser 608. For example, it is determinedwhether the MAC address of the packet is the MAC address of thereceiving device (e.g., STA). In one embodiment, a packet is recognizedif the MAC address of the packet matches the MAC address associated withthe VoWLAN communication device receiving the packet.

In one embodiment, if the MAC address is not recognized, as shown atstep 741, MAC address parser 608 is deactivated. At step 742, the packetis ignored. In response to recognizing a MAC address of the packet, asshown at step 744, MAC device 418 is activated for performing dataprocessing functions, such that MAC device 418 is not activated if theMAC address is not recognized. At step 745, in a particular embodiment,MAC device 418 is deactivated after data processing. In one embodiment,if the MAC address is recognized, as shown at step 746, MAC addressparser 608 is deactivated. At step 748, activity sensor device 602 isactivated upon the passing of the length of the packet. In oneembodiment, process 730 proceeds to step 732 to sense a subsequentpacket.

With reference to FIG. 7A, in one embodiment, as shown at step 704, theVoIP traffic is received at a PHY device, e.g., PHY device 420 of FIG.4, of the wireless transceiver. In one embodiment, a method ofhardware-based beacon processing is provided. In a particularembodiment, the hardware-based beacon processing is performed inconjunction with a beacon processing module (e.g., beacon process module536 of FIG. 5). Hardware-based beacon processing is performed withoutrequiring the use of other components of the MAC device and withoutrequiring the use of a microprocessor.

With reference to FIG. 7C, steps in a process 750 for hardware-basedbeacon processing are illustrated. At step 752, at least one packet isreceived at a hardware beacon processing module, in which the hardwarebeacon processing module is operable without requiring use of amicroprocessor. At step 754, it is determined whether the packet is abeacon packet. If it is determined that the packet is not a beaconpacket, as shown at step 756, the packet is processed by filtering outthe packet. If it is determined that the packet is not a beacon packet,as shown at step 758, in a particular embodiment, at least a portion ofthe MAC device is activated. At step 760, the beacon packet is processedat the activated portion of the MAC device. In a particular embodiment,at step 762, the hardware beacon processing module is deactivated afterthe packet is processed. At step 764, the hardware beacon processingmodule is activated prior to receiving a subsequent packet. In oneembodiment, the hardware beacon processing module is activated by a timeat least long enough to account for clock drift.

With reference to FIG. 7A, at step 706, the VoIP traffic is forwarded toa MAC device, e.g., MAC device 418 of FIG. 4. At step 708, real-timevoice communication functions are performed at the MAC deviceindependent of the microprocessor. It should be appreciated that the MACdevice does not require usage of the microprocessor to perform MACfunctionality. In one embodiment, as shown at step 710, the real-timevoice communication functions performed at the MAC device independent ofthe microprocessor include performing real-time reassembly of the VoIPtraffic.

At step 712, signal processing of the VoIP traffic is performed at themicroprocessor of the voice communication device. At step 714, a voiceapplication for rendering the VoIP traffic is executed at themicroprocessor. In one embodiment, the microprocessor is a RISCmicroprocessor, e.g., RISC microprocessor 402 of FIG. 4. It should beappreciated that signal processing, the voice application and controlfunctions are performed at the microprocessor without the need for aseparate DSP or CPU. At step 716, transmitting rendered voicecommunication to a peripheral device for delivery to a user.

In one embodiment, as shown at step 718, the transmit power of the PHYdevice is controlled based on received VoIP traffic. In one embodiment,the transmit power is controlled by a transmit power control, e.g.,transmit power control 424 of FIG. 4.

Process 770 of FIG. 7D illustrates steps for transmitting VoWLANcommunications at a voice communication device including a singleprocessor. At step 772, voice communication for transmission over theWLAN is received at the voice application. At step 774, signalprocessing of the voice communication at the microprocessor is performedto generate outgoing VoIP traffic.

At step 776, the outgoing VoIP traffic is transmitted to the WLAN overthe wireless connection. In one embodiment, as shown at step 778,real-time voice communication functions are performed at the MAC deviceindependent of the microprocessor. In one embodiment, as shown at step780, the real-time voice communication functions performed at the MACdevice independent of the microprocessor include performing real-timefragmentation of the outgoing VoIP traffic. At step 782, the outgoingVoIP traffic is forwarded to the PHY device for transmission to theWLAN. At step 784, the outgoing VoIP traffic is transmitted at the PHYdevice.

DSP-less Cellular/VoWLAN

FIG. 8 illustrates a block diagram of a cellular/VoWLAN SoC 800, alsoreferred to as CelluLAN SoC 800, including a single microprocessor 810,in accordance with one embodiment of the present invention. CelluLAN SoC800 includes microprocessor 810, WLAN baseband 815, system peripheralcontroller 825, system memory controller 830, and audio codec 835, allcommunicatively coupled over bus 805. It should be appreciated thatCelluLAN SoC 800 may include additional components, as understood bythose of skill in the art. These additional components are not describedherein so as to not obscure the embodiments described herein.

It should be appreciated that bus 805 illustrates that each of thecomponents of CelluLAN SoC 800 are communicatively coupled. However, itshould be appreciated that bus 805 can be implemented as a central bus,as shown, individual interconnections between the individual components,or any combination of buses and individual interconnections. Inparticular, it should be appreciated that bus 805 is not intended to belimited by the shown embodiment.

In one embodiment, microprocessor 810 is operable to perform allnecessary operations associated with VoIP and cellular telephonecommunication, including digital signal processing and control functionsfor VoIP and baseband processing, including digital signal processingand control functions for processing for cellular communications. Inparticular, microprocessor 810 is not a dedicated digital signalprocessor (DSP). In one embodiment, microprocessor 810 is amulti-purpose processor, such as a CPU. In one embodiment,microprocessor 810 is a RISC microprocessor.

It should be appreciated that microprocessor 810 is operable to provideVoIP communications in accordance with the various embodiments describedin FIGS. 1 and 2. Moreover, it should be appreciated that microprocessor810 is operable to provide VoWLAN communications in accordance with thevarious embodiments described in FIGS. 3, 4, 5, 6, 7A, 7B, 7C and 7D.

WLAN baseband 815 is operable to communicate with an IP network over awireless connection external WLAN radio 844 comprising using antenna822, so as to provide VoIP communication over the IP network. In oneembodiment, WLAN baseband 815 includes PHY device 860 and MAC device865. In one embodiment, MAC device 865 is a hardware device that isconfigured to perform real-time voice communication functionsindependent of microprocessor 810. One embodiment of the operation ofMAC device 865 is described in FIG. 5.

System peripheral controller 825 is communicatively coupled to externalsystem peripherals 845 that include additional components that provideadded functionality to CelluLAN SoC 800. System peripheral controller825 is also communicatively coupled to cellular modem 840. System memorycontroller 830 is communicatively coupled to external memory 850 for usein operating CelluLAN SoC 800, and may include volatile memory, such asRAM, SRAM, and SDRAM, and non-volatile memory, such as EEPROM, and NORor NAND. It should be appreciated that external memory 850 may includemultiple types of memory, all of which are represented as externalmemory 850.

Audio codec 835 is operable to encode and decode audio data for use incommunicating voice data using VoIP. It should be appreciated that audiocodec 835 may be implemented as hardware, software, firmware, or anycombination thereof. In one embodiment, audio codec 835 provides forcoupling CelluLAN SoC 800 to an external device for rendering the voicecommunication and for receiving voice communication. In one embodiment,audio codec 835 is coupled to voice headset 838. However, it should beappreciated audio codec 835 may be coupled to many different types ofdevices and interfaces, including but not limited to FXS interfaces, FXOinterfaces, microphones, and speakers.

Cellular modem 840 is operable to receive and transmit cellularcommunications over a cellular network using antenna 842, so as toprovide cellular communication over a cellular network. In oneembodiment, cellular modem 840 includes Global System for MobileCommunications (GSM), General Packet Radio Service (GPRS), and EnhancedData for GSM Evolution (EDGE) functionality for processing for cellularcommunications. In one embodiment, cellular modem 840 is a hardwaredevice that is configured to perform real-time voice communicationfunctions independent of microprocessor 810. One embodiment of thefunctional operation of cellular modem 840 is described in FIG. 5.

It should be appreciated that CelluLAN SoC 800 provides for voicecommunication over a WLAN and a cellular network without requiring theuse of a dedicated DSP as well as a general-purpose microprocessor. Inparticular, CelluLAN SoC 800 is operable to perform voice processing onthe general-purpose microprocessor 810 (e.g., a RISC microprocessor).Microprocessor 810 is configured to provide all voice processing andcontrol functionality for operation of CelluLAN SoC 800.

FIG. 9 illustrates a block diagram of a CelluLAN communication device900 including a single RISC microprocessor 902, in accordance withanother embodiment of the present invention. CelluLAN communicationdevice 900 includes CelluLAN SoC 901, which operates in a similar manneras CelluLAN SoC 800 of FIG. 8 to provide VoWLAN and cellular telephonyfunctionality where voice processing and control functionality for theVoIP is performed without a separate DSP microprocessor. CelluLAN SoC901 includes two buses, a high-speed bus 912 and a peripheral bus 911.

CelluLAN SoC 901 includes LCD controller 929 which may be coupled to LCD949, internal memory 930, external memory controller 931 which may becoupled to external memory 950, such as external flash memory (e.g.,EEPROM, NOR Flash, SDRAM, and ASRAM), Direct Memory Access Controller(DMAC) 928, Security Module 927, cellular transceiver 926 which iscoupled to cellular RF antenna 952, and WLAN transceiver which iscoupled to WLAN RF antenna 951, which communicate over high speed bus912.

CelluLAN SoC 901 also includes power management unit (PMU) 912 which iscoupled to battery subsystem 941, CPU timers 913, watchdog 914, RTC 915,GPIO 916 that may be coupled to ringer 941, I2C interface 917 which maybe coupled to I2C devices 942, Universal Serial Bus (USB) interface 918which may be coupled to digital debug port 943, enhanced Joint TestAction Group (JTAG) interface 919 which may be coupled to host data port944, keyboard/mouse interface (KMI) 920 which may be coupled to akeyboard and/or mouse 945, Universal Asynchronous Receiver-Transmitterinterface 921 which may be coupled to test/debug port 946, SubscriberIdentity Module (SIM) card interface (SCI) 922 which may be coupled toSIM card 947, and Advanced Audio Codec Interface (MCI) 923 which may becoupled to audio codec 948, which communicate over peripheral bus 911.

High speed bus 912 and peripheral bus 911 are communicatively coupledover bus bridge (BRG) 924. The operations of various components ofCelluLAN communication device 900 are understood by those of skill inthe art. These components are not described herein so as to not obscurethe embodiments described herein.

In one embodiment, RISC microprocessor 902 is operable to perform allnecessary operations associated with VoIP communication, includingdigital signal processing and control functions, and cellularcommunication. In particular, RISC microprocessor 902 does not requirethe use of a dedicated DSP to perform signal processing. RISCmicroprocessor 902 is configured to provide all voice processing andcontrol functionality for operation of CelluLAN communication device900. In one embodiment, RISC microprocessor 902 includes MemoryManagement Units (MMU) 903, I-cache 904, and Instruction Tightly CoupledMemory (I-TCM) 905 for managing instructions, MMU 909, D-cache 908, andD-TCM 907 for managing data, Real time trace support interface (INT)906, and high speed bus interface 910.

CelluLAN communication device 900 is operable to provide VoIPcommunication over an IP network over a wireless connection usingantenna 951 and to provide cellular communication over a cellularnetwork using antenna 952. In one embodiment, VoIP traffic transmittedthrough WLAN transceiver 925, both in transmission and reception, arecontrolled by a PHY device and a MAC device. In one embodiment, the MACdevice is a hardware device that is configured to perform real-timevoice communication functions independent of RISC microprocessor 902.One embodiment of the operation of an exemplary MAC device is describedin accordance with FIG. 5.

CelluLAN communication device 900 is operable to receive and transmitcellular communication at cellular transceiver 926. In one embodiment,cellular transceiver includes a baseband processing module forperforming real-time voice communication functions independent of themicroprocessor. One embodiment of the functional components of anexemplary baseband processing module is described in accordance withFIG. 10.

FIG. 10 illustrates a block diagram of a cellular transceiver 1000, inaccordance with one embodiment of the present invention. Basebandprocessing is executed at layer 1 of cellular transceiver 1000. Layer 1includes debug and trace operation 1002, layer 1 controller 1004,baseband processing module 1006, transmitter 1008, receiver 1010, andadditional operations 1012.

In one embodiment, baseband processing module 1006 is compliant withGlobal System for Mobile Communications (GSM), General Packet RadioService (GPRS), and Enhanced Data for GSM Evolution (EDGE). In oneembodiment, receiver 1010 is configured to perform synchronization,channel estimation, channel decoding, and decryption on incoming voicetraffic. In one embodiment, transmitter 1008 is configured to performchannel encoding, burst formatting, encryption, and modulation onoutgoing voice traffic. In one embodiment, additional operations 1012include synchronization, automatic gain control (AGC), automaticfrequency control (AFC), timing advancement, and power control. In oneembodiment, the layer 1 operations are performed in hardware that isconfigured to perform real-time voice communication functionsindependent of RISC microprocessor 902.

Receiver 1010 and transmitter 1008 are communicatively coupled to speechprocessing voice codecs 1014, for providing voice communication. Speechprocessing voice codecs 1014 are communicatively coupled to microphoneand speaker/headset 1016 for rendering and receiving voicecommunication. Additional operations 1012 are communicatively coupled tocellular RF antenna 952. Additional operations 1012 are operable tocontrol the performance and operation of cellular RF antenna 952.

Layers 2 and 3 of cellular transceiver 1000 include Real-Time OperatingSystem (RTOS) 1020, applications 1022, GSM data services 1024, GSM 1026,GPRS 1028, and EDGE 1030.

With reference to FIG. 9, in one embodiment, CelluLAN SoC 901 is alsooperable to provide transmit power control for proactively controllingpower to reduce power dissipation while in transmit mode for VoWLANcommunications. In one embodiment, the transmit power control isperformed as described in accordance with transmit power control 424 ofFIG. 4. In one embodiment, CelluLAN SoC includes components forproactive power control of WLAN transceiver. In one embodiment, theproactive power control is performed as described in accordance withFIG. 6 and the accompanying description.

FIG. 11 is a flow chart illustrating a process 1100 for providingCelluLAN communication using a single microprocessor, in accordance withan embodiment of the present invention. In one embodiment, process 1100is carried out by processors and electrical components under the controlof computer readable and computer executable instructions. The computerreadable and computer executable instructions reside, for example, indata storage features such as computer usable volatile and non-volatilememory. However, the computer readable and computer executableinstructions may reside in any type of computer readable medium.Although specific steps are disclosed in process 1100, such steps areexemplary. That is, the embodiments of the present invention are wellsuited to performing various other steps or variations of the stepsrecited in FIG. 11. In one embodiment, process 1100 is performed by aCelluLAN communication device, e.g., CelluLAN SoC 800 of FIG. 8 orCelluLAN communication device 900 of FIG. 9.

At step 1102, voice communication is received at a voice communicationdevice, e.g., CelluLAN communication device 900 of FIG. 9. At step 1104,it is determined whether the voice communication is VoWLAN communicationor cellular communication. If the voice communication is VoIP trafficreceived from a WLAN, as shown at step 1106, the VoWLAN traffic isprocessed using a single microprocessor. In one embodiment, the VoIPtraffic is processed according to processes 700, 730, 750 and 770 ofFIGS. 7A, 7B, 7C and 7D, respectively.

Alternatively, if the voice communication is cellular voicecommunication received from a cellular network, process 1100 proceeds tostep 1108. In one embodiment, as shown at step 1108, the real-time voicecommunication functions are performed at a cellular transceiverindependent of the microprocessor. In one embodiment, the real-timevoice communication functions include: synchronizing the voicecommunication, performing channel estimation on the voice communication,performing channel decoding on the voice communication, and decryptingthe voice communication.

At step 1110, the cellular communication is processed using themicroprocessor. It should be appreciated that the same microprocessor isused in executing steps 1106 and 1110, and that the voice communicationdevice only includes one microprocessor for performing voice-relatedoperations. In one embodiment, the microprocessor is a RISCmicroprocessor. At step 1112, rendered voice communication istransmitted to a peripheral device for delivery to a user.

At step 1114, outgoing voice communication for transmission over thecellular network is received. At step 1116, the outgoing voicecommunication is transmitted using the cellular transceiver. In oneembodiment, transmitting the outgoing voice communication includesperforming channel encoding on the outgoing voice communication,performing burst formatting on the outgoing voice communication,encrypting the outgoing voice communication, and modulating the outgoingvoice communication.

Embodiments of the present invention provide a voice communicationdevice for providing VoWLAN functionality with a device including asingle processor. Embodiments of the present invention provide a VoWLANcommunication device including a single processor and without a DSPmicroprocessor. Embodiments of the present invention provide a VoWLANcommunication device including a MAC device implemented in hardware forperforming real-time communication MAC functionality independent of themicroprocessor. Embodiments of the present invention provide a VoWLANcommunication device that is operable to provide passive listening andprovide enhanced transmit power control for providing enhanced powerconsumption.

Furthermore, embodiments of the present invention provide a voicecommunication device for providing cellular and VoWLAN functionality,also referred to herein as CelluLAN functionality, with a deviceincluding a single processor. Embodiments of the present inventionprovide a CelluLAN communication device including a single processor andwithout a DSP microprocessor. Embodiments of the present inventionprovide a CelluLAN communication device including a MAC deviceimplemented in hardware for performing real-time communication MACfunctionality independent of the microprocessor. Embodiments of thepresent invention provide a CelluLAN communication device that isoperable to provide passive listening and provide enhanced transmitpower control for providing enhanced power consumption. Embodiments ofthe present invention provide a cellular transceiver for performingreal-time voice communication functions independent of themicroprocessor.

Moreover, embodiments of the present invention provide ahardware-centric MAC device for performing real-time data communicationfunctions without requiring a microprocessor. Embodiments of the presentinvention provide a communication device operable to provide passivelistening for reducing power consumption of the communication device.Embodiments of the present invention provide a communication deviceoperable to perform hardware beacon processing without requiring the useof a microprocessor for reducing power consumption of the communicationdevice.

The foregoing descriptions of particular embodiments of the presentinvention have been presented for purposes of illustration anddescription. They are not intended to be exhaustive or to limit theinvention to the precise forms disclosed, and many modifications andvariations are possible in light of the above teaching. The embodimentswere chosen and described in order to best explain the principles of theinvention and its practical application, to thereby enable othersskilled in the art to best utilize the invention and various embodimentswith various modifications as are suited to the particular usecontemplated. It is intended that the scope of the invention be definedby the claims appended hereto and their equivalents.

1. An apparatus comprising: a network physical layer device; an activitysensor device for sensing a packet, sensing a silence-to-energy event ata beginning of said packet, and activating the network physical layerdevice from a shutdown state in response to sensing said packet and saidsilence-to-energy event, and wherein said activity sensor device isconfigured for being deactivated subsequent sensing said packet suchthat said activity sensor device is deactivated at least for a length ofsaid packet; said network physical layer device for decoding a physical(PHY) header portion and a Media Access Control header portion of aheader of said packet following activation from said shutdown state; amedia access controller comprising a fixed hardware media access planeimplementing IEEE 802.11 series media access control functionality andcomprising a receive packet process unit coupled to a programmablemicroprocessor through a bus interface; and a media access controladdress parser for receiving the Media Access Control header portion ofsaid packet, for processing the Media Access Control header portion ofsaid packet, for activating the media access controller from a shutdownstate in response to recognizing a Media Access Control address withinsaid Media Access Control header portion, and for deactivating thenetwork physical layer device responsive to the media access controladdress parser not recognizing the Media Access Control address and suchthat the media access controller is not activated if the media accesscontrol address parser does not recognize the Media Access Controladdress, wherein the media access controller is operable, afteractivation, to perform the media access control functionality withoutusing the programmable microprocessor and to provide data from thepacket to the programmable microprocessor through the bus interface. 2.The apparatus as recited in claim 1, wherein said physical layer deviceis deactivated subsequent decoding said header of said packet.
 3. Theapparatus as recited in claim 1 wherein said activity sensor comprises:a radio frequency (RF) and mixed signal model for receiving a signalcomprising said packet.
 4. A method comprising: sensing a packet and asilence-to-energy event at an activity sensor device; responsive to saidsensing, activating a network physical layer device from a shutdownstate, said activity sensor device performing said activating; decodingat least a physical layer portion and a media access control layerportion of a header of said packet at said network physical layerdevice, said media access control layer portion of the header includinga destination media access control address; deactivating said activitysensor device for at least a length of said packet; determining whethersaid destination media access control address from the media accesscontrol layer portion of the header of said packet is recognized, thedetermining performed by a media access control address parser forreceiving the media access control header portion of said packet, forprocessing the media access control header portion of said packet;responsive to recognizing said destination media access control address,activating a fixed function hardware media access controller comprisinga fixed hardware media access plane implementing IEEE 802.11 seriesmedia access control functionality and comprising a receive packetprocess unit coupled to a programmable microprocessor through a businterface, from a shutdown state for performing data processingfunctions such that said fixed function hardware media access controlleris not activated if said destination media access control address is notrecognized; deactivating the network physical layer device responsive tothe media access control address parser not recognizing the destinationmedia access control address; reactivating said activity sensor deviceupon a passing of said length of said packet; and performing, at thefixed function hardware media access controller, after activation, mediaaccess control functionality without using the programmablemicroprocessor and to provide data form the packet to the programmablemicroprocessor.
 5. The method as recited in claim 4 further comprising:deactivating said physical layer device subsequent said decoding atleast said header of said packet at said physical layer device; andreactivating said physical layer device upon receiving a header from asubsequent packet from said activity sensor sensing said subsequentpacket.
 6. The method as recited in claim 4 further comprising:deactivating said media access control address parser subsequent saiddetermining whether said media access control address of said packet isrecognized; and reactivating said media access control address parserfor receiving said header portion from said network physical layerdevice.